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Long Island Indicator Service Inc

Precision Tool Repairs, Sales & Spare Parts







Internal Bore Micrometers
sorting through the options


Brown & Sharpe Style A INTRIMIK / IMICRO

For direct analog readings, like a micrometer, of bore diameters, using 3-point measurement. This eliminates errors associated with comparator gages such as dial bore gages. These are premium quality tools made in Switzerland by Tesa, sold in the US with the Brown & Sharpe brand name. These intrimiks are available to read diameters from .275" to 12". With optional extensions, the depth of the bore can be as much as 40 inches. Metric versions read from 3.5 mm to 300 mm with a 100 cm depth extension available on larger models. It will not be possible to measure to the very bottom of blind holes with this particular model (use the Etalon ingage instead, see below). For calibration purposes, one setting ring (not included) will be required per tool. Quality rating: A+

Tesa Micromaster INTRIMIK with digital display

The same as Style A, but with an LCD display. Available individually up to 11.80" or in sets. Exercise caution when buying electronic gages. They're expensive and although they have advantages with easier read outs, they often times can not be economically repaired. Their useful life is likely to be shorter than the mechanical versions of the same gage. Ask us to fax you details.



These Swiss-made internal micrometers offer 3-point contact to the bottom of blind holes. They're self-centering and self-aligning for consistent readings. Ranges are from .600" to 2.400" with a measuring depth of only 2.5". An optional 6" extension is available. These gages feature mechanical digital readings in .0002" graduations. Interchangeable measuring arms extend the range from 2.400" to 4.800" These arms can be bought separately. All can be bought as complete sets. Metric versions measure from 15 mm to 120 mm. See page 174 for full details.


Tesa TRIOMATIC Electronic Bore Gage

This is the new digital electronic version of Style B showing Swiss craftsmanship at its finest. Twelve different tools will measure from .600" to 4.800" and are available individually or in sets.

Exercise caution when buying electronic gages. Although they have advantages with easier read outs, they often times can not be economically repaired. Their useful life is likely to be shorter than the mechanical versions of the same gage. At present time, there is no repair service in the US for these gages. If they are damaged the manufacturer will offer you a rebuilt unit in exchange. Uses two SR44 batteries. Ask us for details.


Mechanical INTRIMIK cases

All styles, individual and sets, for digital or analog. Your choice of mahogany or molded plastic available for most sizes. Ask us for details.



For deep hole measurement. Available in 4", 6", 20" and 40" (100 mm, 150 mm, 500 mm, 1000 mm) lengths. It's possible to combine extensions but better to use a single extension of the right length. Ask us for details.


Setting Rings for INTRIMIK and INGAGES


Setting rings are an absolute necessity for these gages. Buy one ring for each tool, preferably for the middle of the tool's range or, better yet, for the exact dimension you need to measure. If you must skimp, then buy one ring for the high end of one gage so that it can double for the low end of the next gage. Available in any custom size. See details on page 163.


Etalon INGAGE 531 internal bore micrometer

Direct readings, with extended anvils to reach the bottom of blind holes. These have a vernier reading of .0001" with accuracy of plus/minus .0001". Each set has an extension (4" or 6") for measuring deep bores. Extra extensions can be added. The irregular spacing of the anvils can be used to measure out-of-roundness. 18 gages will measure the range from .188" to 4.005" or 4.78 mm to 100.10 mm. They're available singly or in sets. Larger models reading in .0005" extend the range from 4" to 6" (99.8 mm to 300.2 mm). These Etalon ingages were also sold under the Lufkin name during the 1960's. For details and more information refer to Etalon Ingage 531.


Dial Bore Gages

Mitutoyo 511-932 Dial Bore Gauge, 0.7"-6" Range, 0.0001" Graduation, +/-0.0008" Accuracy

Dial bore gages are comparators which do not offer direct readings. They feature an indicator which shows deviations in .0001" or 0.002 mm attached to a measuring stem with one retractable anvil. This allows for 2-point measurement. For more information see

What will go wrong?


These Swiss-made tools are sturdy and reliable gages but they can be dropped, the anvils will wear after lots of use, many users will overtighten the gage causing metal stress, and dirt will get into the digital counter, if it has one.

What are the solutions? Keep them in their case so they won't roll to the floor; anvil wear is inevitable but these can be replaced; use the ratchet or friction mechanism to avoid overtightening; and keep them clean.

If you use the gage in a dirty environment, you'll get longer use out of the vernier (non-digital) gage. The digital counter is quicker to read but should be used in clean environments only. As for electronic digital gages, buy them only if you're sure the positives outnumber the negatives. They tend to be easier to use by unskilled workers, quicker to read, but the potential for damage is high. It will probably be impossible to repair any but the most recent models of electronic gages.


Other options


Mitutoyo Holtest

We can also recommend Mitutoyo Holtest Series 368 which in some instances has distinct advantages. On those models which feature carbide anvils, the anvils can easily be replaced when they are worn.

Microtest 3-point Internal Micrometer

Swiss made, highly reliable and very sturdy gages. Just six different heads will measure from 30 to 400 mm (metric only) compared to the dozen or more heads that would be required from any other manufacturer. Generally hard to find in the US, but they can be ordered on request.

Using a setting ring


1. Use a setting ring which falls within the gage's range.

2. Expand the 3 feelers of the gage inside the setting ring. Use the friction or ratchet end of the gage to avoid overtightening.

3. If the vernier readings don't line up, you can turn the sleeve (there's a small hole on the sleeve which is designed to make this easy; in some models you may have to loosen and tighten a screw). When the vernier readings correspond to the setting ring size, then the gage is ready for use.

4. Direct readings can now be taken. These steps should be repeated periodically.

On page 163 you will find a selection of setting rings suitable for use with these gages.


Imports from India


Currently offered by SPI and other catalog houses. These sell for nearly half the price but we question the wisdom in investing in this "bargain." For one thing, the gages and setting rings do not arrive with calibration certificates (that's your responsibility). For another, you can be certain that repair parts do not exist. One small mishap and you'll have no choice but to add them to your local land-fill.




Long Island Indicator Service Inc
14 Sarah Drive — Hauppauge NY 11788 — USA

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This page's most recent revision: 25 JANUARY 2018
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Original photographs and content copyright 2018 by JWGrum


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